In conventional electronic devices such as, for example, computer systems, electronic components are mounted on circuit cards, which are assembled into electronic circuit card modules. The circuit card modules are usually inserted into a chassis of an electronic device and, typically, plugged via a connector into an enclosure having a backplane or a motherboard. The circuit card modules may also include additional circuit cards, which are called mezaanine cards. The mezzanine card is electrically connected to the main card via a connector.
There are several standards defining properties of circuit card modules, for instance, VMEbus, SEM-E, PCI, cPCI standards, etc. The standards encompass mechanical specifications such as card dimensions, connector specifications, etc, along with electronic specifications such as bus structures, signal functions, timing, signal voltage levels, and master/slave configurations. These specifications enable different modules of the same standard supplied from different manufacturers to plug into any enclosure of the same standard, and provide for communications between different modules.
Proper cooling of electronic components in general, and those mounted on circuit cards in particular, is essential in electronic devices, wherein excessive beat generated by the electronic components can cause malfunctions and failure thereof. Depending on the manner of cooling, conventional circuit cards and, consequently, circuit card modules, are generally classified under convection cooled and conduction cooled types. In general, in the framework of the same standard, conventional convection and conduction cooled card modules are different in construction, however, both meeting the same standard electronic specifications.
Convection cooled card modules are mounted within the chassis of an electronic device in such a way as to allow the free flow of cooling air over electronic components to dissipate excess heat generated. The flow of air is usually provided by fan.
Convection cooled card modules are typically used when there are no severe requirements for protection of their cards from harsh environment such sand, dust, humidity etc. They also cannot be used in closed electronic devices where air ventilation is impossible.
Under the above conditions, conduction cooled card modules are conventionally utilized. In such modules, heat generated by electronic components of a circuit card is absorbed by an internal heat transmitting layer thereof, often made of copper, and thereby forwarded to a dissipation device, being commonly called a heat sink, usually constituted by the chassis in which the module are mounted. Since a conduction cooled circuit card does not require an air exchange over its electronic components, it can be hermetically sealed within its module or rather used in a sealed electronic device, as it happens most often.
Typically, the chassis is formed with a slot defined between front, back, and base walls thereof and the circuit card module is mounted in this slot so that its back surface is in contact with the back wall of the slot to transfer thereto the heat. In conventional circuit card modules, a wedgelock is typically used to keep the module in place, the wedgelock being mounted to the module with its one surface and abutting the front surface of the slot of the chassis with its other surface. Typically, each surface of the wedgelock is in partial contact with the circuit card module or the chassis.
U.S. Pat. No. 6,246,582 and U.S. Pat. No. 6,212,075 disclose a system for improving heat dissipation from a circuit card module by using a wedgelock with an increased surface adapted for contacting the walls of the slot.